When a tape cassette is inserted into the VTR of the so-called front loading type through a cassette inlet formed in the front panel of the apparatus, the cassette is transported by a cassette loading device first horizontally and then downward and is finally placed on a pair of reel supports arranged inside the apparatus.
Although a drive motor specific to the cassette loading device is usually used as the power source for the device, a VTR has been proposed wherein the power source for a tape loading mechanism for withdrawing the magnetic tape from the cassette and winding the tape around a rotary head cylinder is used also as the power source for the cassette loading device so as to make the recorder compact, lightweight and less expensive to make (Unexamined Japanese Patent Publication SHO No. 61-289572).
FIG. 19 shows the cassette loading device of the proposed VTR. A cassette holder 2 is movable by being guided along an L-shaped guide slit 102 formed in each side plate 101 on a chassis 1. A loading motor 5 is coupled to a gear lever 107 through a pulley mechanism 103, clutch 104, worm 105, and a train of gears including a worm wheel 106. The gear lever 107 includes a gear portion 110 meshing with the gear train and a lever portion 108 in engagement with the cassette holder 2 and supported by the same shaft as the gear portion 110. A torsion spring 111 is provided between the gear portion 110 and the lever portion 108.
The clutch 104 is engaged or disengaged by the rotation of a cam plate 109 which is coupled to the clutch 104 by a lever mechanism 112.
The tape loading mechanism (not shown), which is already known, is coupled to the pulley mechanism 103.
When a tape cassette 11 is to be loaded, the clutch 104 is engaged, through which the rotation of the loading motor 5 is transmitted to the gear lever 107 to thereby transport the cassette 11 with the cassette holder 2 inwardly of the recorder along the guide slit 102.
After the cassette holder 2 reaches the terminal end of the path of its travel along the guide slit 102, the worm 105 is slightly driven, thereby elastically deforming the torsion spring 111. The repellent force of the spring depresses the holder 2 at the terminal end of the path, whereby the cassette 11 is completely loaded.
Although the repellent force of the torsion spring 111 acts as a torque to reversely rotate the worm wheel 106 in this state, the torque is withstood by the frictional resistance between the meshing teeth of the worm 105 and the worm wheel 106, with the result that the cassette holder 2 is locked at the terminal end of the path of travel of the holder 2.
On completion of cassette loading, the clutch 104 is disengaged. The magnetic tape is thereafter loaded in place by the operation of the loading motor 5.
However, the VTR is very complex in construction and large-sized owing to the provision of the pulley mechanism 103, clutch 104, lever mechanism 112, cam plate 109, etc. and therefore has the problem that this disadvantage offsets the advantage of using a single motor for both the cassette loading device and the tape loading mechanism.
Furthermore, the clutch 104 is disengaged while the cassette is in its completely loaded position, so that when the device is subjected to an external impact, the worm wheel 106 is likely to disengage from the worm 105 against the frictional resistance and rotate to unlock the cassette holder 2.